Film Transparency and Opacity Measurements

Transparency is an important and commonly measured characteristic of food packaging films. Mixed definitions of film transparency and opacity have been used in the literature with or without considering the film thickness. In this short communication, we demonstrated that light absorbance or transmittance is independent of film thickness in highly transparent films. Therefore, we recommend the use of percent transmittance at 600 nm (transparency) or over the visible light range (color and transparency) to characterize the appearance of films. For translucent films that absorb and/or scatter light, the absorbance at 600 nm divided by the film thickness may be used to quantify the film opacity.